Esterases (also referred to as lipases) are enzymes that cleave triglycerides (fats or lipids) or esters into carboxylic acids (fatty acids) and mono- and di-glycerides. For an explanation of the slightly different definitions given to lipases and esterases see Siezen, R. J. and van den Berg, (37). A pregastric esterase is an esterolytic or lipolytic enzyme secreted by the oral tissues of mammals. Animal esterases in an unpurified form called rennet have been used in the production of dairy food products and, in particular, the production of enzyme modified cheeses or EMCs. (8), (9), (10), (17), (18), (33), (40), and (41). In particular, cheeses like Romano and Provolone have a “peppery” or “piccante” flavor due to the fatty acid composition created by the enzyme in the rennet paste. (26), (37).
Traditionally EMCs are prepared by esterases obtained from the gullet of slaughtered animals from which a rennet paste or powder is obtained. The rennet is used to treat whey to impart flavor into the cheese product. Kid pregastric estersase (kPGE or kid PGE) in rennet paste is contaminated with proteins which are found in the gullet of the kid and other substances used in the preparation of the rennet. It would be useful to have an uncontaminated kPGE to produce EMC's. Such EMC's could be produced in a manner acceptable to kosher and vegetarian consumers. A recombinant kPGE (rKPGE) could be produced in very pure form free of the other substances found in the present commercial rennet formulations.